The present invention relates to an optical recording medium including a substrate and a signal recording layer provided on the substrate and in which an information signal recorded on the signal recording layer is reproduced optically or by detecting a change of the reflected light focused onto the signal recording layer, and to a disc cartridge encasing the optical recording medium.
As one of the conventional recording media for audio and video information, optical discs, from which recorded information is read using a light beam or to which information is written using a light beam, are widely used. Since such an optical disc is formed from a single plate-like substrate, it can easily be handled and has a larger storage capacity than other recording media such as magnetic tapes, etc. Therefore, the optical discs are widely used as media for recording audio and video information, computer-processed data, etc.
Information processing units, such as computers, have been designed more and more compact with an increasingly smaller internal space of installation for a recording and/or reproducing apparatus using an optical recording medium such as an optical disc or the like. That is, there is a demand for a smaller design of such a recording and/reproducing apparatus.
There are various types of portable or carry-on recording and/or reproducing apparatuses for recording and/or reproduction of audio and video information. For a higher portability, it is also demanded that the apparatuses be of a more compact design.
For such a smaller recording and/or reproducing apparatus, a recording medium used in the apparatus should be correspondingly smaller while having a larger storage capacity.
It is therefore an object of the present invention to provide a novel optical recording medium designed smaller while having a larger storage capacity, and a disc cartridge in which the optical recording medium is encased.
It is another object of the present invention to provide an optical recording medium having a larger storage capacity while contributing to a more compact design of a recording and/or reproducing apparatus in which the optical recording medium is used, and a disc cartridge encasing the optical recording medium.
It is a further object of the present invention to provide an optical recording medium designed smaller and positively mountable on a rotation driving mechanism to be rotatable along with the rotation driving mechanism, and a disc cartridge encasing the optical recording medium.
In an embodiment, an optical recording medium according to the present invention includes a substrate and a signal recording layer provided on the substrate, an information signal being recorded on the signal recording layer. The optical recording medium has a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium. A ratio between the information signal recording area and a non-recording area is 3.4 or more. A storage capacity is at least 2 GB (gigabytes) or more.
The above optical recording medium has formed at the center thereof a center hole around which there is formed an annular table-abutment being convex to one side of the medium and in which a hub or clamping plate is fixed.
In an embodiment, an optical recording medium according to the present invention includes a substrate and a signal recording layer provided on the substrate, wherein an information signal recorded on the signal recording layer is reproduced by detecting a change of the reflected light focused onto the signal recording layer. The optical recording medium has a diameter of over 38 mm and under 52 mm and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium. A storage capacity is at least 1 GB or more.
The above optical recording medium has formed at the center thereof a center hole around which there is formed an annular table-abutment being convex to one side of the medium and in which a hub or clamping plate is fixed.
In an embodiment, an optical recording medium according to the present invention has an annular table-abutment for placement on a disc table of a rotation driving mechanism, and a hub which is to be attracted by a magnet disposed on the disc table, whereby the medium can be rotated along with the disc table.
In an embodiment, an optical recording medium according to the present invention is a read-only optical recording medium. It includes a substrate, formed to a thickness of 0.4 to 0.6 mm by injecting resin within a mold prepared by stamping a stamper having formed thereon a pit pattern in which the recording track pitch and smallest-pit length are about 1.4 times larger than those in a first optical recording medium with a storage capacity of at least 2 GB including a substrate, and a signal recording layer provided on the substrate, and in which information signal recorded on the signal recording layer is reproduced by detecting a change of the reflected light focused onto the signal recording layer; and a light-transparent sheet which is 0.05 to 0.1 mm in thickness and having on one side thereof a pit pattern, formed by thermally stamping a pit-pattern stamper, where a signal recording layer is formed. In the optical recording medium, the substrate and sheet are joined to each other with their respective pit-pattern sides placed in a face-to-face relation through a light-transparent layer of 20 to 35 xcexcm. The first optical recording medium having a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm, an information signal recording area defined thereon extending outwardly from a radial position of 12.5 mm or less from the center of the medium, a ratio in diametrical length of 3.4 or more between the information signal recording area and a non-recording area, and a storage capacity of at least 2 GB. It has a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm. An information signal-recorded area defined thereon extends outwardly from a radial position of 12.5 mm or less from the center of the medium. A storage capacity is a half or less of that of the first optical disc recording medium.
In an embodiment, the optical recording medium is a read-only type. It has a diameter of over 38 mm and under 52 mm and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium.
In an embodiment, a disc cartridge according to the present invention comprise an optical disc including a substrate; a signal recording layer provided on the substrate and in which an information signal recorded on the signal recording layer is reproduced by detecting a change of the reflected light focused onto the signal recording layer, the optical disc having a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm, an information signal recording area defined thereon extending outwardly from a radial position of 12.5 mm or less from the center of the optical disc, a ratio of 3.4 or more between the information signal recording area and a non-signal recording area, and a storage capacity of at least 2 GB or more; and a rectangular cartridge in which the optical disc is encased. In the disc cartridge, a writing and/or reading access opening is formed in a side thereof to which an optical pickup to focus a light beam on at least the optical disc is opposite through which a radially extending portion of the optical disc is exposed, and a central opening is also formed through which a center hole formed at the center of the optical disc is exposed. The writing and/or reading access opening is formed deviated to one lateral side from the middle point of the front side of the cartridge.
In an embodiment, a disc cartridge according to the present invention encases an optical disc including a substrate and a signal recording layer provided on the substrate, and in which an information signal recorded on the signal recording layer is reproduced by detecting a change of the reflected light focused onto the signal recording layer. In an embodiment, a disc cartridge has a diameter of over 38 mm and under 52 mm and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium. Its storage capacity is at least 1 GB.
A disc cartridge according to the present invention encasing the above-mentioned read-only optical disc has a reading access opening formed only in a lower half.